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Setting Up Transactional Replication: A Step-by-step Guide

General concepts

Replication is the process whereby data is copied between databases on the
same server or different servers connected by LANs, WANs, or the Internet.
Microsoft SQL Server replication uses a publish, distributor and subscribe
metaphor.

Publisher is the server or database that sends its data to another server
or database.

Subscriber is the server or database that receives data from another server
or database.

Distributor is the server that manages the flow of data through the replication
system. This server contains the distribution database.

Publisher contain publication/publications.
Publication is a collection of one or more articles that is sent to a subscriber
server or database. Article is the basic unit of replication and can be a table
or a subset of a table.

Subscription is the group of data that a server or database will receive. This
can be one or more publications. There are push and pull subscriptions.
Push subscription is subscription when the publishing server will periodically
push transactions out to the subscribing server or database.
Pull subscription is subscription when the subscribing server will periodically
connect to the distribution database and pull information.

Microsoft SQL Server support the following replication topologies:

Central publisher

Central subscriber

Central publisher with remote distributor

Publishing subscriber

Central publisher

This is one of the most common replication topologies. One server is
configured as Publisher and Distributor and another server/servers
is configured as Subscriber/Subscribers.

Central subscriber

This is a common topology in data warehousing. Many servers or databases
replicate their data to a single central server or database.

Central publisher with remote distributor

In this topology distribution database resides on the another server
than publisher. This topology uses for performance reasons when the
level of replication activity increases or the server or network
resources become constrained.

This topology requires separate Microsoft SQL Server installations,
one for the Publisher and one for the Distributor.

Publishing subscriber

This is a dual role topology. In this topology, the publishing server
or database also subscribes to another server or database. In this scenario
two servers publish the same data. This is useful when a Publisher must send
data to Subscribers over a slow or expensive communications link.

Checking necessary conditions

Check the following before setting up transactional replication:

1. Remember that Microsoft SQL Desktop Edition supports only subscriptions to
transaction replications. So you must use Microsoft SQL Standard,
Enterprise or Small Business Server (SBS) editions to publish transaction
replications. So for publish transaction replications you must have
Windows NT Server, Windows NT Server Enterprise Edition or
Windows NT Small Business Server (on Windows NT WorkStation and
Windows 95/98 you may install only Microsoft SQL Desktop Edition version).

2. The Localsystem account has no access to shares on the network as it
isn't an authenticated network account.
So if you want to setting up replication you must change the account
the MSSQLServer and SQLServerAgent services runs under to a account
with the Windows NT administrator's rights.

3. Only members of the sysadmin server role can set up and configure
replication, so if you have not this rights, you can not set up
replication.

4. You must uncheck trunc. log on chkpt option, if you want to set up
transactional replication.

5. Allocate adequate log space for each database that will be published
in transactional replication.

6. Allocate adequate disk space for the distribution database.

7. Ensure the server that is being replicated to is defined as a remote server.

If you want to have continuous replication that will send the data as soon
as possible, you can choose Continuously option otherwise choose schedule
option. The shedule option can be very effective when delaing with slow
links. Select the Continuously option and click the Next button.

Initialize subscription if it's needed.

Click Next button.

Click Finish button to create the subscription.
Now you will receive the following: